import java.util.Scanner;

public class Test2_16 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        System.out.print("Enter the length of the side: ");
        double s = sc.nextDouble();
        // 六边形面积计算公式
        double area = 3 * Math.sqrt(3) / 2 * s * s;

        System.out.print("The area of the hexagon is " + String.format("%.4f", area));
    }
}
